Limitation of energy wavelengths applied during 3d printing

ABSTRACT

In one example of the disclosure, a system for limitation of energy wavelengths applied during 3D printing includes an energy source to provide energy to a target zone during a 3D printing operation. The system includes a filter chamber through which the energy is to pass before arriving at the target zone. The system includes a filter chamber control component to selectively modify the contents of the filter chamber to limit the wavelengths of energy that can pass through the filter chamber based upon type of the target zone.

RELATED APPLICATION

This application claims priority to PCT Application No. PCT/EP2015/072101 filed on Sep. 25, 2015, entitled “FILTERING SYSTEM”, the entire contents of which are hereby incorporated herein by reference.

BACKGROUND

Many systems and processes use portions of the electromagnetic spectrum. For example, ultra-violet radiation may be used to cure or harden materials comprising photo polymers, such as adhesives, printing fluids, or the like. Other systems, for example, may use infrared radiation to heat a target.

DRAWINGS

FIG. 1 is an illustration of a system to limit of energy wavelengths applied during 3D printing according to one example;

FIG. 2 is an illustration of a system to limit of energy wavelengths applied during 3D printing according to another example;

FIG. 3 is an illustration of a 3D printer including a wavelength selection apparatus according to one example;

FIG. 4 is a block diagram depicting a memory resource and a processing resource to implement examples of implementation of a wavelength selection component and a filter chamber control component.

FIG. 5 is a flow diagram outlining a method to restrict energy wavelengths applied during 3D printing according to one example.

FIG. 6 is a flow diagram outlining a method to restrict energy wavelengths applied during 3D printing according to another example.

DETAILED DESCRIPTION

Introduction:

Certain systems and processes include applying ultra-violet radiation, infrared radiation, or other energy to a target zone in an additive manufacturing technique. For instance, in some examples of 3D printing objects may be generated on a layer-by-layer basis by selectively solidifying a portion of a layer of a build material. In certain examples of 3D printing, various printing agents may be utilized. For instance, an energy absorbing fluid, such as a fusing agent, may be deposited onto a layer of build material. When energy is applied to the layer of build material, portions of the build material on which fusing agent were deposited absorb sufficient energy to melt, fuse, or sinter, whereas those portions of the build material on which no fusing agent was deposited will not melt, fuse, or sinter. In other examples of 3D printing, an additional agent, such as a detailing agent, may be utilized in conjunction with a fusing agent. In another example, a detailing agent may be delivered interspersed with a fusing agent to enable 3D object properties to be modified.

One challenge in 3D printing is to afford flexibility to utilize different printing agents and different build materials and yet maintain a satisfactory printing speed. To address these issues, various examples described in more detail below provide a system and a method for limiting wavelengths of energy applied to a target zone during 3D printing. In one example, a system for limiting wavelengths of energy applied to a target zone includes an energy source to provide energy to a target zone during a 3D printing operation and a filter chamber through which the energy is to pass before arriving at the target zone. The system additionally includes a filter chamber control component to selectively modify the contents of the filter chamber to limit the wavelengths of energy that can pass through the filter chamber based upon the type of the target zone (e.g., a printing agent, or other target zone).

In examples, the target zone may be a printing agent applied over a build material via an inkjet ejection process. In examples, the target zone may be a fusing agent applied over a build material, and wherein the application of the fusing agent and the provision of energy is to fuse the build material. In examples, the target zone may be detailing agent applied over a build material, wherein the application of the detailing agent is to modify a degree of coalescence of a portion of the build material onto which the detailing agent has been delivered or has penetrated. In examples, the filter chamber control component may be to selectively control filling or emptying of the filter chamber with a filter material, the filter material having predetermined energy filtering characteristics predetermined as appropriate for the applicable target zone.

In examples wherein a set of printing agents (e.g., a fusing agent, a detailing agent, and/or a combination of fusing agents and/or detailing agents) are applied during a printing operation, the filter chamber control component may be to selectively modify the contents of the filter chamber in accordance with the types of the set of printing agents.

In examples, the system may include a plurality of filter chambers through which energy from the energy source can pass through to the target zone, wherein each filter chamber is associated with a different filter material having predetermined filtering characteristics and is selectively controllable to be independently filled or emptied of its associated filter material.

In this manner, the disclosed examples provide for an efficient and easy to use method and system for limitation of energy wavelengths applied during 3D printing. The disclosed examples enable a matching of energy wavelengths to an identified absorption property of a particular printing agent without mixing in additives with the printing agents. Accordingly, users of 3D printers should appreciate increased printing speeds and increased energy efficiency enabled by implementation of the disclosed examples. Further, as the disclosed example enable use of multiple printing agents without the expense of additives, sharper edges and increased color possibilities are made possible and the quality of the printed product may be increased.

The following description is broken into sections. The first, labeled “Components,” describes examples of various physical and logical components for implementing various examples. The second section, labeled “Operation,” describes implementation of various examples.

Components:

FIGS. 1, 2 and 3 depict examples of physical and logical components for implementing various examples. In FIGS. 1-3 various components are identified as components 114 and 208. In describing components 114 and 208 focus is on each component's designated function. However, the term component, as used herein, refers generally to a combination of hardware and programming to perform a designated function. As is illustrated later with respect to FIG. 4, the hardware of each component, for example, may include one or both of a processor and a memory, while the programming may be code stored on that memory and executable by the processor to perform the designated function.

FIG. 1 is a block diagram depicting components of a system 102 to enable limitation of energy wavelengths applied during 3D printing. In this example, system 102 includes an energy source 104, such as an infrared lamp. Hereinafter, reference may be made to infrared lamps, although it will be understood that this is no way limiting, and in other examples other kinds of electromagnetic radiation energy sources, such as near infra-red energy, microwave energy, ultra-violet (UV) light, halogen light, ultra-sonic energy or the like. Lamp 104 emits energy having a given radiation spectrum. As illustrated in FIG. 1, lamp 104 emits radiation having a first range of wavelengths 106 a, a second range of wavelengths 106 b, a third range of wavelengths 106 c, and a fourth range of wavelengths 106 d. For simplicity while the example shown in FIG. 1 shows four ranges of wavelengths 106 a-d, in a real example any number of ranges of wavelengths may be present. The length of time the energy is applied for, or energy exposure time, may be dependent, for example, on one or more of characteristics of the energy source and characteristics of the target zone 110 to which lamp 104 provides energy wavelengths.

In the example of FIG. 1, system 102 includes a filter chamber 108 through which the energy wavelengths 106 a-d are to pass before arriving at a target zone 110. In an example, filter chamber 108 is a transparent filter chamber. By transparent is meant that the outer walls of the filter chamber are transparent to the energy source, e.g., transparent to at least a portion of the spectrum of radiation emitted by lamp 104. In one example filter chamber 108 may be made from glass or quartz, although other materials may also be suitable. As illustrated in the example of FIG. 1, since filter chamber 108 itself is transparent, if the filter chamber 108 is empty energy wavelengths 106 a-d emitted from lamp 102 would pass through filter chamber 108 to reach the target zone 110.

In examples, the target zone 110 to which the energy wavelengths are to arrive at may be a printing agent applied over a build material. As used herein, a “printing agent” refers generally to fusing agent or a detailing agent or a combination of fusing agents and/or detailing agents utilized by a 3D printer in a 3D printing operation. As used herein, a “build material” refers generally to a material that is to be deposited in layers to by a 3D printer to create a 3D product. As used herein, a “3D printer” is synonymous with a “3D printing device”, or additive manufacturing system, and refers generally to a device utilized to generate a three-dimensional (“3D”) object by forming successive layers of build material based upon digital instructions derived from a 3D model or other electronic data source. In one example, a build material may be or may include a powdered semi-crystalline thermoplastic material. In other examples, a build material may be or include, but is not limited to, a powdered metal material, a powdered plastic material, a powdered composite material, a powdered ceramic material, a powdered glass material, a powdered resin material, or a powdered polymer material. For instance a 3D printing system may spread an initial layer of build material on the surface of a support platform, and subsequently deposit additional layers of build material upon the initial layer. The exact nature of the build material may be chosen based on criteria that may include, for example, desired properties of a generated 3D object. The term build material is generally used herein to refer to unsolidified build material.

As used herein, a “fusing agent” refers generally to a material that is to be applied on a build material to fuse build materials. As used herein, to “fuse” build materials refers generally to melt, solidify, coalesce, or otherwise bind build materials together. For instance, some 3D printing systems selectively apply, for example using a printing mechanism, a fusing agent on a layer of build material in a pattern corresponding to a layer of the object being generated. By applying energy to the whole, or a substantial portion, of the layer of build material, those portions of the build material on which fusing agent is deposited absorb sufficient energy to cause the temperature of those portions to rise such that fusing, and subsequent solidification, of the build material occurs. Those portions of the build material on which no fusing agent is deposited do not absorb sufficient energy to cause fusing hence do not solidify. In examples, fusing agent is a fluid to be applied to the build material via an inkjet ejection process.

As used herein a “detailing agent” refers generally to a material that is to serve to modify a degree of coalescence of a portion of build material on which the detailing agent has been delivered or has penetrated. In one example, a detailing agent may be delivered adjacent to where a fusing agent is delivered to help reduce the effects of lateral coalescence bleed. In examples, a detailing agent may be used to improve the definition or accuracy of edges or surfaces of the 3D object being printed, and/or to reduce surface roughness. In examples, the detailing agent is a fluid to be applied to the build material via an inkjet ejection process.

System 102 also includes a filter chamber control component 114 that is a combination of hardware and programming to selectively modify filter material content 116 of the filter chamber to limit the wavelengths of energy that can pass through the filter chamber 108 based upon a type of the target zone. As used herein, a “type” of a target zone refers generally to a kind, sort, or category of the target zone. In examples, filter chamber control component 114 is to selectively control filling or emptying of filter chamber 108 with a filter material 116, the filter material having energy filtering characteristics that are predetermined to be appropriate for the target zone 110 (e.g. wherein a type of the target zone is a particular printing agent that lamp's 104 energy is being applied to). In examples, filter chamber control component 114 is to selectively control filter chamber 108 to be filled or emptied of its associated filter material 116 so as to attain filter characteristics that are predetermined to be appropriate for filtering the wavelengths 106 a-d of energy emitted by lamp 104 so as to effectively influence or affect target zone 110.

In certain examples, filter chamber 108 may be a sealed chamber that is in fluid communication, through a conduit, with a pump. The pump may be controlled by filter chamber control component 114 to pump a filter material 116, such as a fluid, from a filter material content storage vessel to the interior of the filter chamber 108. The pump may also be controlled by filter chamber control component 114 to remove filter material 116 from the filter chamber 108 by pumping the filter material 116 in the filter chamber 108 back to the filter material content storage vessel. The pump may be controlled, for example, in response to a control signal sent by the filter chamber control component 114.

Continuing with the example of FIG. 1, filter chamber control component 114 may selectively control filter chamber 108 to be filled or emptied of filter material content 116 (e.g., a fluid including but not limited to CO₂, CH₄, and N₂0) so as to attain filter chamber 108 characteristics that are predetermined to be appropriate for filtering the first range of wavelengths 106 a and fourth range of wavelengths 106 d of energy emitted by lamp 104 so as to allow the second range of wavelengths 106 b and the third range of wavelengths 106 c to pass through the filter chamber 108 and influence or affect the target zone 110. In a particular example, the target zone may be a printing agent with a violet or purple coloration, and the filter material content 116 utilized in the filter chamber 108 to filter to the appropriate energy wavelengths may be a CO₂ gas. In another particular example, the printing agent may have a red or purple coloration, and the filter material content 116 utilized in the filter chamber 108 to filter to the appropriate energy wavelengths may be a CH₄ gas. In another particular example, the target zone may be a printing agent have a blue or green coloration, and the filter material content 116 utilized in the filter chamber 108 to filter to the appropriate energy wavelengths may be a N₂0 gas.

In certain examples, the target zone 110 may be a fusing agent and an inkjet, or printhead, ejection process is utilized to apply the fusing agent to a build material. In such examples, lamp 104 may provide energy to the fusing agent to fuse portions of the build material on which fusing agent is deposited. In other examples, target zone 110 may be a detailing agent, and an inkjet, or printhead, ejection process is utilized to apply the detailing agent.

FIG. 2 is a block diagram depicting another example of components of a system 102 to enable limitation of energy wavelengths applied during 3D printing. In this example, system 102 includes an ultraviolet light source 104. The ultraviolet light source 104 emits energy having a given radiation spectrum including a first range of wavelengths 106 a, a second range of wavelengths 106 b, a third range of wavelengths 106 c, and a fourth range of wavelengths 106 d. For simplicity while the example shown in FIG. 2 shows four ranges of wavelengths 106 a-d, in a real example any number of ranges of wavelengths may be present. In this example system 102 includes a first transparent filter chamber 108 a, a second transparent filter chamber 108 b, and a third transparent filter chamber 108 c, through which the energy wavelengths 106 a-d would pass before arriving at a printing agent 110. In this example by transparent is meant that the outer walls of the filter chambers are transparent to the ultraviolet light source 104

System 102 includes a wavelength selection component 208 that is a combination of hardware and programming to receive data indicative of a type of target zone and to obtain data indicative of energy absorption properties of the target zone. In examples, wavelength selection component 208 may include core device components. In examples, core device components represent generally the hardware and programming for providing the computing functions for which wavelength selection component 208 is designed. Such hardware may include a processor and memory, a display apparatus, and/or a user interface. The programming may include an operating system and applications.

System 102 additionally includes a filter chamber control component 114 that is to selectively control filling or emptying of first filter chamber 108 a, second filter chamber 108 b, and/or third filter chamber 108 c, with a filter material 116. Filter chamber control component 114 is to selectively control first, second, and/or third filter chambers 108 a-c to be filled or emptied of their associated filter material so as to attain filter characteristics that are predetermined to be appropriate for filtering out the first, second and third ranges of wavelengths 106 b, 106 c, and 106 d of energy emitted by lamp 104, and thereby increase influence upon printing agent 110 by allowing the first range of wavelengths 106 a to reach printing agent 110. In the particular example of FIG. 2, each of filter chambers 108 a, 108 b, and 108 c is a sealed chamber that is in fluid communication, through a conduit 202, with a pump 204. The 204 pump may be controlled by filter chamber control component 114 to pump a filter material 116, such as a fluid, from a filter material content storage vessel 206 to the interior of the attached filter chamber. The pump may also be controlled by filter chamber control component 114 to remove filter material 116 from the attached filter chamber 108 by pumping the filter material 116 in the filter chamber 108 back to the filter material content storage vessel 206.

FIG. 3 is a block diagram depicting another example of a 3D printer including a wavelengths selection component and a filter chamber control component according to one example. In this example, the 3D printer 302 includes a build materials forming apparatus 304 to form a layer of build material 306 on a build platform (not shown). In an example, the build materials forming apparatus 304 may be to provide a first layer of build material on the build platform, and then, after a fusing process enabled by a printing agent application apparatus, to form a second layer of build materials upon the first layer. The thickness of the build layers applied may be varied, wherein using a thicker build layer may result in a faster printing speed and using a thinner build layer may enable higher resolution objects to be generated.

In the example of FIG. 3, 3D printer 302 includes printing agent application apparatus 308 to selectively apply a pattern of printing agent 310 (e.g., a fusing agent, or a detailing agent, or a combination of fusing agents and/or detailing agents), to formed layers of build material 306. In examples, printing agent application apparatus 308 may selectively deliver the printing agent 310 to one or more portions of the surface of a build material layer 306. Printing agent application apparatus 308 may perform the selective delivery of the printing agent 310 in accordance with data derived from a digital model of a three-dimensional object to be created. In one example the patterns define a bitmap. In examples, printing agent application apparatus may perform the selective delivery of the printing agent 310 using any appropriate fluid delivery mechanism, including delivery in droplet form. It should be noted that fusing agent fluids 310 delivered to the surface of the build material may penetrate into the layer 306 of build material. The degree to which a printing agent 310 will penetrate may differ according to various factors. For instance, degree of penetration may depend, for example, on the quantity of printing agent 310 delivered, on the nature of the build material 306, and/or on the nature of the printing agent 310.

In the example of FIG. 3, 3D printer 302 includes an electromagnetic radiation source 312 to apply electromagnetic radiation to the layer of build material according to a spectrum that includes a first range of wavelengths 106 a, a second range of wavelengths 106 b, a third range of wavelengths 106 c, and a fourth range of wavelengths 106 d. For simplicity while the example shown in FIG. 3 shows four ranges of wavelengths 106 a-d, in a real example any number of ranges of wavelengths may be present. In examples electromagnetic radiation source 312 may apply energy that is infra-red or near infra-red energy, microwave energy, ultra-violet (UV) light, halogen light, ultra-sonic energy, or the like. In an example electromagnetic radiation source 312 may be configured to apply energy to a layer of build material 306 for predetermined length of time after printing layer application apparatus 308 has delivered printing agent 310 upon the build material layer 306. The predetermined length of time may be dependent upon on one or more factors including, but not limited to, characteristics of the electromagnetic radiation source, characteristics of the build material, and characteristics of the printing agent.

In the example of FIG. 3, 3D printer 302 includes a wavelength selection apparatus 314. Wavelength selection apparatus 314 includes filter chambers 316 a 316 b 316 c through which the electromagnetic radiation is to pass before arriving at the pattern of printing agent that printing agent 310 application apparatus 308 had applied to the formed layer of build material 306. In this example, each of the filter chambers has a different filter material having predetermined filter characteristics. It should be noted that the choice of three filter chambers for this example of FIG. 3 is not meant to be exclusive, such that in different examples any number of filter chambers with differing filter materials having filter characteristics may be utilized.

Wavelength selection apparatus 314 includes a wavelength selection component 208 to, responsive to receipt of data indicative of a type of the printing agent 310 that is applied to the build material 306, obtain data associated with the printing agent 310 indicative of an electromagnetic absorption profile of the printing agent 310. In the example of FIG. 3, filter chamber control component 114 is to selectively control first, second, and/or third filter chambers 316 a-c to be filled or emptied of their associated filter material so as to attain filter characteristics that are predetermined to be appropriate for filtering out the first and third ranges of wavelengths 106 a and 106 c of energy emitted by electromagnetic radiation source, 312 and thereby influence or affect printing agent 310 in an efficient manner by allowing the second and fourth ranges of wavelengths 106 b and 106 d to reach printing agent 310.

Wavelength selection apparatus 314 also includes a filter chamber control component 114 to selectively modify the contents of the filter chambers 316 a 316 b 316 c in accordance with the obtained data. In examples, according to the data obtained by wavelength selection component 208, filter chamber control component 114 may modify the contents of any of, all of, or none of the filter chambers included in the wavelength selection apparatus (in FIG. 3, filter chambers 316 a 316 b 316 c). In examples, wavelength selection component 208 is to determine, based on the determined filter characteristics, which of the filter chambers 316 a 316 b 316 c should be emptied of its associated filter material, and the filter chamber control component 114 is to control the emptying of a filter chamber of its associated filter material. Further, in examples wavelength selection component 208 is to determine, based on the determined filter characteristics, which of the filter chambers 316 a 316 b 316 c should be filled with its associated filter material, and filter chamber control component 114 is to control the filling of a filter chamber with its associated filter material.

Generation of a three-dimensional object with controllably variable properties is possible by modulating the type of printing agents that are delivered to the layers of build material that are used to generate the object. The choice of printing agents delivered to the layers of build material that are used to generate an object may enable the object to have different object properties. Accordingly, the disclosed examples should, in addition to enabling efficiencies in curing times, should enable the production of high quality objects produced by utilizing multiple printing agents without a need for additive chemicals to accommodate the various printing agents to the available energy source.

In the foregoing discussion of FIGS. 1-3, components 114 and 208 were described as combinations of hardware and programming. Filter chamber control component 114 and wavelength selection component 208 and may be implemented in a number of fashions. Looking at FIG. 4, the programming may be processor executable instructions stored on a tangible memory resource 430 and the hardware may include a processing resource 440 for executing those instructions. Thus memory resource 430 can be said to store program instructions that when executed by processing resource 440 implement components 114 and 208.

Memory resource 430 represents generally any number of memory components capable of storing instructions that can be executed by processing resource 440. Memory resource 430 is non-transitory in the sense that it does not encompass a transitory signal but instead is made up of more or more memory components to store the relevant instructions. Memory resource 430 may be implemented in a single device or distributed across devices. Likewise, processing resource 440 represents any number of processors capable of executing instructions stored by memory resource 430. Processing resource 440 may be integrated in a single device or distributed across devices. Further, memory resource 430 may be fully or partially integrated in the same device as processing resource 440, or it may be separate but accessible to that device and processing resource 440.

In one example, the program instructions can be part of an installation package that when installed can be executed by processing resource 440 to implement components 114 and 208. In this case, memory resource 430 may be a portable medium such as a CD, DVD, or flash drive or a memory maintained by a server from which the installation package can be downloaded and installed. In another example, the program instructions may be part of an application or applications already installed. Here, memory resource 430 can include integrated memory such as a hard drive, solid state drive, or the like.

Continuing at FIG. 4, the executable program instructions stored in memory resource 430 are depicted as wavelength selection module 408 and filter chamber control module 414. Wavelength selection module 408 represents program instructions that when executed by processing resource 440 may perform any of the functionalities described above in relation to wavelength selection component 208 of FIGS. 2-3. Filter chamber control module 414 represents program instructions that when executed by processing resource 440 may perform any of the functionalities described above in relation to filter chamber control component 114 of FIGS. 1-3.

Operation:

FIG. 5 is a flow diagram of implementation of a method for of limiting of energy wavelengths applied during 3D printing. In discussing FIG. 5, reference may be made to the components depicted in FIGS. 1-4. Such reference is made to provide contextual examples and not to limit the manner in which the method depicted by FIG. 5 may be implemented. Energy is provided to target zone during a 3D printing operation (block 502). Referring back to FIGS. 1-3, energy source 104 (FIG. 1) or ultraviolet light source 104 (FIG. 2) or electromagnetic radiation source 312 (FIG. 3) may be utilized when implementing block 502.

Contents of a filter chamber are selectively modified based upon type of the target zone. The filter chamber is to limit the wavelengths of energy that can pass before arriving at the target zone (block 504). Referring back to FIGS. 1-3, filter chamber control component 114 (FIGS. 1-3) or filter chamber control module 414 (FIG. 4), when executed by processing resource 440, may be responsible for implementing block 504.

FIG. 6 is a flow diagram of implementation of a method for of limiting of energy wavelengths applied during 3D printing. In discussing FIG. 6, reference may be made to the components depicted in FIGS. 1-4. Such reference is made to provide contextual examples and not to limit the manner in which the method depicted by FIG. 6 may be implemented. An energy source is utilized to emit a set of wavelengths of electromagnetic radiation towards a printing agent during a 3D printing operation (block 602). Referring back to FIGS. 1-3, energy source 104 (FIG. 1) or ultraviolet light source 104 (FIG. 2) or electromagnetic radiation source 312 (FIG. 3) may be utilized when implementing block 602.

Data indicative of a type of the printing agent is received (block 604). Referring back to FIGS. 2 and 3, wavelength selection component 208 (FIGS. 2-3) or wavelength selection module 408 (FIG. 4), when executed by processing resource 440, may be responsible for implementing block 604.

A database that includes the printing agent and identified wavelengths of electromagnetic radiation stored in association with the printing agent is accessed (block 606). Referring back to FIGS. 1-3, wavelength selection component 208 (FIGS. 2-3) or wavelength selection module 408 (FIG. 4), when executed by processing resource 440, may be responsible for implementing block 606.

The identified wavelengths are utilized to selectively modify fluid filler material of a filter chamber to restrict wavelengths of electromagnetic radiation that pass through the filter chambers to arrive at the printing agent (block 608). Referring back to FIGS. 1-3, filter chamber control component 114 (FIGS. 1-3) or filter chamber control module 414 (FIG. 4), when executed by processing resource 440, may be responsible for implementing block 608.

Conclusion:

FIGS. 1-6 aid in depicting the architecture, functionality, and operation of various examples. In particular, FIGS. 1, 2, and 3 depict various physical and logical components. Various components are defined at least in part as programs or programming. Each such component, portion thereof, or various combinations thereof may represent in whole or in part a module, segment, or portion of code that comprises executable instructions to implement any specified logical function(s). Each component or various combinations thereof may represent a circuit or a number of interconnected circuits to implement the specified logical function(s). Examples can be realized in a memory resource for use by or in connection with processing resource. A “processing resource” is an instruction execution system such as a computer/processor based system or an ASIC (Application Specific Integrated Circuit) or other system that can fetch or obtain instructions and data from computer-readable media and execute the instructions contained therein. A “memory resource” is a non-transitory storage media that can contain, store, or maintain programs and data for use by or in connection with the instruction execution system. The term “non-transitory” is used only to clarify that the term media, as used herein, does not encompass a signal. Thus, the memory resource can comprise a physical media such as, for example, electronic, magnetic, optical, electromagnetic, or semiconductor media. More specific examples of suitable computer-readable media include, but are not limited to, hard drives, solid state drives, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory, flash drives, and portable compact discs.

Although the flow diagrams of FIGS. 5 and 6 show specific orders of execution, the order of execution may differ from that which is depicted. For example, the order of execution of two or more blocks or arrows may be scrambled relative to the order shown. Also, two or more blocks shown in succession may be executed concurrently or with partial concurrence. Such variations are within the scope of the present disclosure.

It is appreciated that the previous description of the disclosed examples is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these examples will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the blocks or stages of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features, blocks and/or stages are mutually exclusive. 

What is claimed is:
 1. A system to limit wavelengths of energy applied to a target zone during 3D printing, comprising: an energy source to provide energy to a target zone during a 3D printing operation; a filter chamber through which the energy is to pass before arriving at the target zone; and a filter chamber control component to selectively modify the contents of the filter chamber to limit wavelengths of energy that can pass through the filter chamber based upon type of the target zone.
 2. The system of claim 1, wherein the target zone is a printing agent applied over a build material.
 3. The system of claim 2, wherein the printing agent is to be applied via an inkjet ejection process.
 4. The system of claim 2, wherein the printing agent is a fusing agent applied over a build material, and wherein the application of the fusing agent and the provision of energy is to fuse the build material.
 5. The system of claim 2, wherein the printing agent is a detailing agent applied over a build material, and wherein the application of the detailing agent is to modify a degree of coalescence of a portion of the build material onto which the detailing agent has been delivered or has penetrated.
 6. The system of claim 1, wherein the filter chamber control component is to selectively control filling or emptying of the filter chamber with a filter material, the filter material having predetermined energy filtering characteristics.
 7. The system of claim 2, wherein a plurality of printing agents are applied during a printing operation, and wherein the filter chamber control component is to selectively modify the contents of the filter chamber in accordance with the types of printing agents.
 8. The system of claim 1, further comprising a wavelength selection component to receive data indicative of the type of the target zone and to obtain data indicative of energy absorption properties of the target zone, and wherein the filter chamber control component is to modify the contents of the filter chamber based upon the obtained data.
 9. The system of claim 1, comprising a plurality of filter chambers through which energy from the energy source can pass through to the target zone, where each filter chamber is associated with a different filter material having predetermined filtering characteristics and is selectively controllable to be independently filled or emptied of its associated filter material.
 10. The system of claim 1, wherein the filter chamber is a filter chamber that is transparent to the energy source.
 11. The system of claim 1, wherein the filter chamber is connected to a pump which is connected to a filter material content storage vessel, and wherein the pump is controllable to either fill the filter chamber with filter material from the filter material content storage vessel or to empty the contents of the filter chamber into the filter material content storage vessel.
 12. A 3D printer, comprising: a first apparatus to form a layer of build material on a build platform; a second apparatus to selectively apply a pattern of printing agent to the formed layer of build material; an electromagnetic radiation source to apply electromagnetic radiation to the layer of build material; a wavelength selection apparatus, including a filter chamber through which the electromagnetic radiation is to pass before arriving at the printing agent, a wavelength selection component to, responsive to receipt of data indicative of a type of agent, obtain data associated with the printing agent indicative of electromagnetic absorption profile of the fusing agent; and a filter chamber control component, to selectively modify the contents of the filter chamber in accordance with the obtained data.
 13. The 3D printer of claim 12, wherein the wavelength selection apparatus includes multiple filter chambers, each associated with a different filter material having predetermined filter characteristics; and wherein the wavelength selection component is to determine, based on the determined filter characteristics, which of the filter chambers should be filled with its associated filter material, and the filter chamber control component is to control the filling of a filter chamber with its associated filter material.
 14. The 3D printer of claim 12, wherein the printing agent has a color that is one from the set of a red color and a purple color, and the filter material is CH₄.
 15. A method to restrict wavelengths of electromagnetic radiation applied to a printing agent during 3D printing, the method comprising: utilizing an energy source to emit a set of wavelengths of electromagnetic radiation towards a printing agent during a 3D printing operation; receiving data indicative of a type of the printing agent; accessing a database that includes the printing agent and identified wavelengths of electromagnetic radiation stored in association with the printing agent; and utilizing the identified wavelengths to selectively modify fluid filler material of a filter chamber to restrict wavelengths of electromagnetic radiation that pass through the filter chambers to arrive at the printing agent. 